1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 // 5 // Responsible for generating packets on behalf of a QuicConnection. 6 // Packets are serialized just-in-time. Control frames are queued. 7 // Ack and Feedback frames will be requested from the Connection 8 // just-in-time. When a packet needs to be sent, the Generator 9 // will serialize a packet and pass it to QuicConnection::SendOrQueuePacket() 10 // 11 // The Generator's mode of operation is controlled by two conditions: 12 // 13 // 1) Is the Delegate writable? 14 // 15 // If the Delegate is not writable, then no operations will cause 16 // a packet to be serialized. In particular: 17 // * SetShouldSendAck will simply record that an ack is to be sent. 18 // * AddControlFrame will enqueue the control frame. 19 // * ConsumeData will do nothing. 20 // 21 // If the Delegate is writable, then the behavior depends on the second 22 // condition: 23 // 24 // 2) Is the Generator in batch mode? 25 // 26 // If the Generator is NOT in batch mode, then each call to a write 27 // operation will serialize one or more packets. The contents will 28 // include any previous queued frames. If an ack should be sent 29 // but has not been sent, then the Delegate will be asked to create 30 // an Ack frame which will then be included in the packet. When 31 // the write call completes, the current packet will be serialized 32 // and sent to the Delegate, even if it is not full. 33 // 34 // If the Generator is in batch mode, then each write operation will 35 // add data to the "current" packet. When the current packet becomes 36 // full, it will be serialized and sent to the packet. When batch 37 // mode is ended via |FinishBatchOperations|, the current packet 38 // will be serialzied, even if it is not full. 39 // 40 // FEC behavior also depends on batch mode. In batch mode, FEC packets 41 // will be sent after |max_packets_per_group| have been sent, as well 42 // as after batch operations are complete. When not in batch mode, 43 // an FEC packet will be sent after each write call completes. 44 // 45 // TODO(rch): This behavior should probably be tuned. When not in batch 46 // mode, we should probably set a timer so that several independent 47 // operations can be grouped into the same FEC group. 48 // 49 // When an FEC packet is generated, it will be send to the Delegate, 50 // even if the Delegate has become unwritable after handling the 51 // data packet immediately proceeding the FEC packet. 52 53 #ifndef NET_QUIC_QUIC_PACKET_GENERATOR_H_ 54 #define NET_QUIC_QUIC_PACKET_GENERATOR_H_ 55 56 #include "net/quic/quic_packet_creator.h" 57 58 namespace net { 59 60 class QuicAckNotifier; 61 62 class NET_EXPORT_PRIVATE QuicPacketGenerator { 63 public: 64 class NET_EXPORT_PRIVATE DelegateInterface { 65 public: 66 virtual ~DelegateInterface() {} 67 virtual bool ShouldGeneratePacket(TransmissionType transmission_type, 68 HasRetransmittableData retransmittable, 69 IsHandshake handshake) = 0; 70 virtual QuicAckFrame* CreateAckFrame() = 0; 71 virtual QuicCongestionFeedbackFrame* CreateFeedbackFrame() = 0; 72 // Takes ownership of |packet.packet| and |packet.retransmittable_frames|. 73 virtual bool OnSerializedPacket(const SerializedPacket& packet) = 0; 74 virtual void CloseConnection(QuicErrorCode error, bool from_peer) = 0; 75 }; 76 77 // Interface which gets callbacks from the QuicPacketGenerator at interesting 78 // points. Implementations must not mutate the state of the generator 79 // as a result of these callbacks. 80 class NET_EXPORT_PRIVATE DebugDelegateInterface { 81 public: 82 virtual ~DebugDelegateInterface() {} 83 84 // Called when a frame has been added to the current packet. 85 virtual void OnFrameAddedToPacket(const QuicFrame& frame) = 0; 86 }; 87 88 QuicPacketGenerator(DelegateInterface* delegate, 89 DebugDelegateInterface* debug_delegate, 90 QuicPacketCreator* creator); 91 92 virtual ~QuicPacketGenerator(); 93 94 // Indicates that an ACK frame should be sent. If |also_send_feedback| is 95 // true, then it also indicates a CONGESTION_FEEDBACK frame should be sent. 96 // The contents of the frame(s) will be generated via a call to the delegates 97 // CreateAckFrame() and CreateFeedbackFrame() when the packet is serialized. 98 void SetShouldSendAck(bool also_send_feedback); 99 void AddControlFrame(const QuicFrame& frame); 100 101 // Given some data, may consume part or all of it and pass it to the 102 // packet creator to be serialized into packets. If not in batch 103 // mode, these packets will also be sent during this call. Also 104 // attaches a QuicAckNotifier to any created stream frames, which 105 // will be called once the frame is ACKed by the peer. The 106 // QuicAckNotifier is owned by the QuicConnection. |notifier| may 107 // be NULL. 108 QuicConsumedData ConsumeData(QuicStreamId id, 109 const IOVector& data, 110 QuicStreamOffset offset, 111 bool fin, 112 QuicAckNotifier* notifier); 113 114 // Indicates whether batch mode is currently enabled. 115 bool InBatchMode(); 116 // Disables flushing. 117 void StartBatchOperations(); 118 // Enables flushing and flushes queued data which can be sent. 119 void FinishBatchOperations(); 120 121 // Flushes all queued frames, even frames which are not sendable. 122 void FlushAllQueuedFrames(); 123 124 bool HasQueuedFrames() const; 125 126 void set_debug_delegate(DebugDelegateInterface* debug_delegate) { 127 debug_delegate_ = debug_delegate; 128 } 129 130 private: 131 void SendQueuedFrames(bool flush); 132 133 // Test to see if we have pending ack, feedback, or control frames. 134 bool HasPendingFrames() const; 135 // Test to see if the addition of a pending frame (which might be 136 // retransmittable) would still allow the resulting packet to be sent now. 137 bool CanSendWithNextPendingFrameAddition() const; 138 // Add exactly one pending frame, preferring ack over feedback over control 139 // frames. 140 bool AddNextPendingFrame(); 141 142 bool AddFrame(const QuicFrame& frame); 143 144 void SerializeAndSendPacket(); 145 146 DelegateInterface* delegate_; 147 DebugDelegateInterface* debug_delegate_; 148 149 QuicPacketCreator* packet_creator_; 150 QuicFrames queued_control_frames_; 151 152 // True if batch mode is currently enabled. 153 bool batch_mode_; 154 155 // Flags to indicate the need for just-in-time construction of a frame. 156 bool should_send_ack_; 157 bool should_send_feedback_; 158 // If we put a non-retransmittable frame (namley ack or feedback frame) in 159 // this packet, then we have to hold a reference to it until we flush (and 160 // serialize it). Retransmittable frames are referenced elsewhere so that they 161 // can later be (optionally) retransmitted. 162 scoped_ptr<QuicAckFrame> pending_ack_frame_; 163 scoped_ptr<QuicCongestionFeedbackFrame> pending_feedback_frame_; 164 165 DISALLOW_COPY_AND_ASSIGN(QuicPacketGenerator); 166 }; 167 168 } // namespace net 169 170 #endif // NET_QUIC_QUIC_PACKET_GENERATOR_H_ 171
